1. Field of the Invention
This invention relates to electrophotographic printers and specifically to toner cartridges for use with electrophotographic printers.
2. Background of the Invention
In an electrophotographic, or laser printer, ink is supplied in the form of toner which is in powder form stored in a container, or hopper, within an replaceable cartridge. In the Optra series of printers manufactured by Lexmark International, Inc. the standard size toner cartridge contains enough toner to print approximately 17,600 print sheets.
In a toner cartridge, the cost of the toner itself is relatively small in comparison to the total cost of the entire toner cartridge. A need, therefore, exists for a toner cartridge and method of modifying a Lexmark Optra series toner cartridge to include a larger volume of toner therein.
According to the manner in which a Lexmark Optra series laser printer operates, the level of toner in the toner cartridge is determined by the printer. The manner in which encoder wheel on the toner cartridge operates to determine the level of toner is described in U.S. Pat. No. 5,634,169, assigned to Lexmark International, Inc., Lexington, Ky., incorporated herein by reference.. If additional toner is supplied to the toner cartridge, an error message results and the printer becomes inoperational. A need, therefore, exists for a method of modifying a Lexmark Optra series laser printer toner cartridge so that additional toner can be supplied without receiving an error message.
It is an object of the present invention to provide a high yield laser printer toner cartridge of the type including a hopper with a shaft having a first end and a second end extending through the hopper, such that a paddle disposed in the hopper rotates about the shaft, an encoder wheel secured to the first end of the shaft extending from the hopper and a drive gear having a face and a limit positioned on the face secured to the second end of the shaft, an arbor including a gap on its outer circumference bounded on one end by a shoulder secured to the second end of the shaft such that the limit is positioned in the gap of the arbor, a torsion spring having a first segment and a second segment where the first segment is mounted onto the drive gear and the second segment is mounted onto the arbor, the improvement including positioning a stop on the face of the drive gear between the limit and the shoulder.
It is a further object of the present invention to provide a method of modifying a laser printer toner cartridge to produce a high yield laser printer toner cartridge of the type including a hopper containing a volume of toner therein, a shaft having a first end and a second end extending through the hopper such that a paddle disposed in the hopper rotates about the shaft, an encoder wheel secured to the first end of the shaft extending from the hopper and a drive gear having a face and a limit positioned on the face secured to the second end of the shaft, an arbor including a gap on its outer circumference bounded on one end by a shoulder secured to the second end of the shaft such that the limit is positioned in the gap of the arbor, a torsion spring having a first segment and a second segment where the first segment is mounted onto the drive gear and the second segment is mounted onto the arbor, the improvement wherein the improvement includes positioning a stop on the face of the drive gear between the limit and the shoulder and adding an additional volume of toner to the hopper.
Further objects, features, and advantages of the present invention will be apparent to those skilled in the art upon examining the accompanying drawings and upon reading the following description of the preferred embodiments.